Photographic process



' Oct. 27, 1964 FIG. I.

J G. FlDELMAN 3,154,416

Pl-IOTOGRAPHIC PROCESS Filed March so, 1961 Blue @Light Green & Light Red & Lighl n lllllllllllllllllll ll IIIWWIIIII ransm lg Blue Absorbs Blue Bleached Absorbs Greeh Bleached (Film Or Paper) EFFECT OF LIGHT OF THE PRIMARY COLORS FIG. 2;

While &

Cyan Dye C Mugenla Dye 8 Yellow Dye A Subslrcle Tronsmils Blue Eighl l Absorb; Re

r reen Absorbs lue Absor s l TransmilsGreen Transmlls Red EFFECT OF PROJECTING WHITE LIGHT THROUGH FILMAFTER EXPOSURE OF FIG. I.

Yellow lnrerlayer Magenta lnlerlayer Film Base FIG. 3.

Yellow lnferlay Cyan Film

Magenta FIG. 4.

INVENTOR J George Fidelman ATTORNEY United States Patent 3,154,416 PHQTQGRAEHEC PRGQESS .l George Fidelnzan, Fort Lauderdale, Fla, assignor to Horizons incorporated, @levelaud, Ohio, a corporation of New Jersey Filed Mar. 30, 1961, Ser. No. 99,413 6 Claims. (Cl. 96-73) This invention relates to a non-silver direct-positive dye-bleach photographic process wherein both full-color transparencies and full-color prints on a white opaque substrate are produced with images which are sharp and distinct, and to the materials from which the color transparencies and color prints are produced.

In patent application Serial No. 50,696 (fled August 19, 1960, jointly by me) which issued as United States lPatent 3,104,973 on September 24, 1963, and in patent application Serial No. 47,849 (filed August 5, 1960, by Sprague, Fichter and Hamilton) which issued as United States Patent 3,102,027 on August 27, 1963, of which I have knowledge, photosystemsare described comprising photolytically sensitive halogen-containing organic compounds and cyanine and merocyanine dyes which bleach out on exposure to light of a suitable wavelength.

in attempting the practice of the invention described in the aforesaid patent applications on a semi-commercial or production basis it was found that in many instances the photosensitivity and color separation obtainable with one batch of film was not reproducibly obtainable with succeeding materials prepared and processed in the identical manner from identical source materials.

The principal object of the present invention is to provide means whereby images which are intense, sharp cutting, and in brilliant colors, with good color separation, yieldin a very high-quality color rendition are reproducibly obtained and which eliminate the loss in sensitivity and color-separation occasionally experienced in directpositive non-silver dye-bleach photographic systems.

One object of this invention is to provide a non-silver direct-positive dye-bleach photographic system capable of producing full color photographic prints.

Still another object of the invention is to provide a relatively simple photosystem wherein full-color direct positive prints are produced solely by the action of the exposing light without any chemical development.

Still another object of the invention is to provide a process wherein the colored image produced may be stabilized and fixed by a simple heat treatment.

A still further object of this invention is to provide a process for producing positive transparencies in full color, either for projection or for color prints when coated on a white opaque substrate.

A still further object of the invention is to provide a simple photosystem for the production of office copy.

These and other objects are achieved by utilizing the present photographic system in any of the several alternative modes of practicing the invention described below and illustrated in the accompanying drawings in which:

FIGURE 1 diagrammatically illustrates the efiect of exposure of a tripack to light of various colors;

FIGURE 2 schematically shows the resulting direct positive obtained after the exposure of FIGURE. 1; and

FIGURES 3 and 4 each show a modified tripack which may be used in place of that shown in FIGURE 1.

As described in the above noted applications, a direct positive full color print may be obtained byutilization of an integral tripack of three sensitive layers. comprises a sensitive coating containing a dye of the proper color mixed with a suitableactivating agent and dispersed in a convenient film-former. Any of the layers may also include extraneous materials added for specific purposes, e.g. to alter the speed of the system. When Each layer 3, l 54,4 l h Patented Get. 27, 1964 "ice the sensitive coating is exposed image-wise to light of the Wavelength absorbed by the dye, the dye is bleached in the area struck by the light, with the result that a directpositive image remains in the layer. By proper selection of the dyes an accurate color rendition is obtained by a subtractive process.

For example, a green sensitive layer may be obtained with the process, using a magenta dye, which is, of course, green absorbing, transmitting blue and red freely. When such a film is exposed in a camera, for example, to light reflected from colored objects, the action of green light on this layer is to bleach the magenta dye. It is not, of course, aifected by blue or red light; light of these wavelengths is not absorbed by the sensitive material. What is obtained in this layer, therefore, is a minus-green record which corresponds, for example, with the magenta printer in conventional color printing processes.

Similarly, a blue-sensitive layer, comprising a yellow dye, is bleached on exposure to blue light, giving a minusblue record which corresponds to the yellow printer in conventional printing processes.

Finally, a red-sensitive layer, containing a cyan dye, is bleached by red light, giving a minus-red image corresponding to the cyan printer in color printing processes.

When these three sensitive layers are superimposed in an integral tripack it will be seen that, since all three of the dyes transmit freely in the areas in which they do not absorb, light of a particular color will aifect only a single layer. The result of the subtractive reflection of light from a white, opaque substrate on such developed layers is the reflection of light of the same color as that originally exposing the material.

This may be further illustrated by reference to FIG- URE 1.

The three-layer integral tripack, depicted in FIGURE 1 consists of three light-sensitive layers superimposed, one on top of the other. The coating nearest the substrate is a blue-sensitive yellow dye labelled A, the coating on top of this is a green-sensitive magenta dye labelled B, and the topmost coating is a red-sensitive cyan dye labelled C.

The effect of light of the primary colors, blue, green and red, on such a coating is illustrated by the diagram under the areas marked Blue Light, Green Light, and Red Light. Since the red-sensitive layer, C, and the green-sensitive layer, B, transmit blue light freely, no efiect is obtained with blue light until layer A is reached; whereupon the yellow dye is bleached in this area. Therefore, in the area of the film struck by blue light, there remain the cyan layer and the magenta layer. After fixing, which may be accomplished by short heating, if such a developed film is viewed under White light,

the cyan layer will absorb red light; the magenta layer will absorb green light; while both the cyan layer and magenta layer will transmit blue freely, as shown in Fl URE 2.

In this way, the result is reflection or transmission of only blue in the area which was originally struck by blue light; in other words, a direct positive is obtained. Similarly, when green light strikes the three-layer coating, the cyan dye will transmit the green freely while the magenta dye will absorb the green light and be bleached. Since the cyan dye and the yellow dye are still intact and the former will absorb red while the latter will absorb blue, the net reflection or transmission from the bleached layer will be green; again, a direct positive. Finally, in the area struck by red light, the cyan dye will absorb this radiation and be bleached. The greenand blue-sensitive layers will be unaffected. The magenta dye will absorb the green light, the yellow dye will absorb the blue light, and the net reflection from the combined three layers will be red.

As indicated above, the three-layer integral tripack depicted in FIGURE 1 comprises three light-sensitive layers superimposed on one another on a suitable base material. To insure that the sensitivity of the tripack is not diminished or even entirely lost by undesirable reactions, which may occur when materials from more than one layer of the tripack are permitted to intermingle even to a limited extent, I have devised modes of preparation of the tripack which preserve the photosensitivity and which yield images with good color separation.

In one embodiment of the invention intermingling of the dye-bleach materials of the tripack shown in FIGURE 1 is avoided by selecting solvents, vehicles and carriers so that successive layers are formulated from materials which do not dissolve or penetrate into the solid substrate to which they are applied. In a second embodiment shown in FIGURES 3 and 4 intermingling of the dye-bleach materials is avoided by interposing a barrier layer between successive photosensitive layers.

The following is a typical coating procedure for the preparation of a color-sensitized film and is intended to be illustrative of a generally applicable procedure:

(1) A film of a suitable substrate, eg a mil sheet of clear or white cellulose acetate film, is flooded on one side for three seconds with a cyan dye solution; the excess solution is then poured off.

(2) The coated film is dried for about one minute in a stream of air at 50 C., e.g. by suspending the wet coated film in a suitable drying oven.

(3) Next, a barrier layer is formed on the cyan layer by coating a plastic layer onto the cyan layer from a suitable coating solution.

(4) The plastic layer is dried by baking for two. minutes at 50 C., as in Step 2.

(5) Then a magenta dye solution is coated on top of the plastic layer after drying.

(6) A barrier layer is applied to the magenta layer by coating a plastic layer onto the magenta layer from a suitable coating solution.

(7) The plastic layer is dried by baking as before.

(8) A yellow dye solution is then coated on the second plastic barrier layer.

(9) The coated film is dried in a stream of air at 50 C. for about one minute.

In the preferred method outlined above all three photosensitive layers are located on one side of the film, this being a necessity on white opaque substrates. 7 When a transparent base is utilized, it is equally feasible to put cyan and yellow on one side and magenta on the other, or cyan and magenta on one side and yellow on the other, using a suitable plastic interlayer between each pair of adjacent dye layers.

The essential and necessary compositional limitation which must be observed is that, in laying down any layer, care must be exercised that the liquid coating formulation be free from any material which acts as a solvent for the dye in the layer on which the liquid is being deposited.

As in the aforesaid applications, in the bleachout-dye layer the essential constituents are (1) an organic halogen-containing compound such as those represented by the general formula RC-X wherein R is a monovalent radical selected from the group consisting of hydrogen, chlorine, bromine, iodine, alkyl, substituted alkyl, aryl and substituted aryl, and each X is selected from the group consisting of Cl, Br and I; and (2) a dye which bleachs when exposed to light of a suitable wavelength in the presence of the compound (1).

Although I do not wish to be bound by any specific theory, it is possible that a complex may be formed between the halogen-containing compound and the bleachout dye which may require less energy to raise it to an excited state to permit the desired photolytic reaction to take place than when such complexes do not form.

The dyes of the present invention (when a suitable organic halogen compound is present) are bleached when 4 exposed to light, giving as described above a direct positive image. Furthermore, the bleachout process of this invention requires no solvent extraction for fixation to render the dye image permanent; a short heating period only is needed to destroy any sensitivity remaining in the system after exposure to visible light.

Organic halogen-containing compounds which are suitable in the photographic systems of this invention include carbon tetrabrornide, pentabromoethane, carbon tetrachloride, carbon tetraioclide, iodoform, bromoform, chloroform, hexachlorethane, bromotrichloromethane, benzotribromide, and similarly polyhalogenated hydrocarbon compounds in which at least three halogen atoms are attached to a single carbon atom.

The bleachout dyes useful in the photosystems of this invention are polymethine dyes such as the cyanines, carbocyanines, merocyanines, styryl dyes and their higher vinylene homologs.

Other plastic supports may be used in place of the 10 mil cellulose acetate, which is preferred. For example plastic coated paper, Mylar (a polyester), polyvinylchloride and a variety of other plastics could be used, provided the bleachout dye solution is suitably formulated.

Example 1 The coating procedure for producing a color-sensitized film was as follows:

A sheet of lO-mil clear cellulose acetate film was flooded on one side for three seconds with a solution of 37 mg. of the cyan dye, l',3-diethylthia-4'-carbocyanine iodide, and 10 mg. of carbon tetrabromide in 7 cc. of a mixture of equal parts by volume of methanol, acetone and dimethylformamide, then excess solution was poured off. The dyed wet film was dried for one minute in a stream of air at 50 C.

Next, a plastic interlayer solution, consisting of a 10% solution of ethylcellulose (Hercules Type N, 4.5 c.p.s.) in toluene was poured over the first coating and, after 3 seconds contact, the excess solution was poured off and the coated strip was dried (baked) for two minutes in a stream of air at 50 C.

Then a solution of 12 mg. of the magenta dye, 3-ethyl- 5- 1-ethyl-2 1H) -pyridylidene) -ethylidene] rhodanine, and 0.3 g. carbon tetrabromide in 7 cc. of toluene was coated on the plastic interlayer deposited as related above, excess solution being poured 01f after contact of 3 seconds.

Finally, on the reverse (and uncoated) side of the film, a solution of 15 mg. of the yellow dye, 5-[3-ethyl- 2(3H) benzoxazolylidene) ethylidene] 3 phenyl-2- phenylimino-4-thiazolidone, and one gram of CBr in 7 cc. of a mixture of equal parts by volume of methanol, acetone and dimethylformamide, was coated, the excess being poured off, and the film being dried for a third time in a stream of air at 50 C. for one minute.

The resulting film was exposed under a multicolored subject using an RFL No. 2 photoflood lamp at a distance of 10 inches as light source. The transparency was accurately duplicated as a direct positive on exposure for 10 minutes.

In place of the ethylcellulose plastic used for the separating layer, other suitable plastics may be substituted,

e.g. methylcellulose, polystyrene, and the like.

Example 2 seconds contact with excess solution, the film was hung up to dry for two minutes in a stream of air at 50 C.

Then a solution of mg. of the yellow dye, 5-[(3- ethyl-2(3H)-benzoxazolylidene)-ethylidene] 3 phenyl Z-phenylimino-4-thiazolidone, and one gram of pentabromoethane in 7 cc. of toluene was applied in a similar manner to the same side of the film, and dried as above.

Next, another layer of ethylcellulose was applied as in the second step above.

Finally, a cold solution of 15 mg. of the magenta dye, 3 ethyl 5 [(l-methyl-Z(lI-l)-pyridylidene) ethylidene]-rhodanine, and 0.2 g. of pentabromoethane in 7 cc. toluene was applied to the same side of the film, dried in a stream of cool air until dry to the touch and then oven-dried as above. The yellow dye was not affected by cold toluene in the short time involved, although it dissolved quite readily in hot toluene, and remained in solution on cooling to room temperature.

In place of the ethylcellulose plastic used for the separating layer, other suitable plastics may be substituted, e.g. methylcellulose, polystyrene, and the like.

Example 3 The following coatings were applied successively to one side of a sheet of l0-mil white-pigmented cellulose acetate, in the order mentioned:

The sheet was first flooded for three seconds with a solution or" 7 mg. of the cyan dye, 1,3-diethylthia-4- carbocyanine iodide, and mg. of carbon tetrabromide in 18 cc. of a mixture of equal parts of acetone, ethanol, and dimethylformamide. The sheet was dried in a stream of air at 50 C. for one minute.

Next, a solution of 8 mg. of the yellow dye, 5-[ (Ii-ethyl- 2(3H) benzoxazolylidene) ethylidene] 3 phenyl-Z- phenylimino-4-thiazolidone, 4 g. of carbon tetrabromide and 5 cc. of a 2% ethyl cellulose in toluene solution in 14 cc. of toluene (heated solution to dissolve dye, then cooled to room temperature) Was coated and similarly dried.

Finally, a solution of 8 mg. of the magenta dye, 3-ethyl 5 [(1-ethyl-2(ll-l) pyridylidene)-ethylidene]- rhodanine, 5 cc. of 2% ethyl cellulose-toluene solution, and 0.3 g. carbon tetrabromide was applied on top of the previous two coatings and dried in a stream of air at room temperature.

The sensitized sheets thus obtained were used to make contact prints, in color, from color transparencies and also to make projection-enlargement copies, in color, of a number or" -min. color-transparency subjects.

In place of the ethylcellulose plastic used for the separating layer, other suitable plastics may be substituted, e.g. methylcellulose, polystyrene, and the like.

The products obtained in each of the above examples had a sharper color separation than those usually obtained in practicing the inventions in the above noted patent applications.

Having now described my invention in accordance with the patent statutes, 1 claim:

1. An article comprising a support member and at least two photosensitive layers supported thereon as follows:

a binder-free first photosensitive layer on said substrate consisting essentially of (1) an organic halogen containing compound selected from the group consisting of alkyl and aralkyl compounds in which at least three halogen atoms are attached to a single carbon atom, said halogens being selected from the group consisting of Cl, Br and I, and (2) a bleachable polymethine dye selected from the group consisting of cyanines, carbocyanines, merocyanines, styryl dyes and their high vinylene homologs;

a photoinsensitive layer of clear plastic coated on said first layer, said plastic having been deposited on said first layer from a solution of said plastic formulated from materials which do not dissolve or pene trate into the first layer when the solution was applied thereto;

and a second photosensitive layer on said photoinsensithe layer, said second photosensitive layer consisting essentially of an organic halogen containing compound selected from the group consisting of alkyl and aralkyl compounds in which at least three halogen atoms are attached to a single carbon atom, said halogens being selected from the group consisting of Cl, Br and l, and a bleachable polymethine dye selected from the group consisting of cyanines, carbocyanines, merocyanines, styryl dyes and their higher vinylene homologs and sensitive to light of Wavelengths different from those to which the dye in said first layer is sensitive, the organic halogen containing compounds in said first and second layers being present in an amount suflicient to accelerate the bleaching out of said dyes when exposed to radiation absorbed by said dyes.

2. The article of claim 1 including in addition a second photoinsensitive layer as a film of clear plastic deposited on said second photosensitive layer from a solution formulated of materials which do not dissolve or penetrate into said second photosensitive layer when the solution is applied thereto and a binder-free third photosensitive layer consisting essentially of organic halogen compound selected from the group consisting of alkyl and aralkyl compounds in which at least three halogen atoms are attached to a single carbon atom, said halogens being selected from the group consisting of Cl, Br

and I, and bleachable polymethine dye selected from the group consisting of cyanines, carbocyanines, merocyanines, styryl dyes and their higher vinylene homologs and wherein said dye is sensitive to light of wave-lengths difierent from those to which the dyes in said first and second layers are sensitive.

3. The article of claim 1 including in addition a binder-free third photosensitive layer on the uncoated face of said support member; said third photosensitive layer consisting essentially of organic halogen compound selected from the group consisting of alkyl and aralkyl compounds in which at least three halogen atoms are attached to a single carbon atom, said halogens being selected from the group consisting of Cl, Br and I, and bleachable polymethine dye selected from the group consisting of cyanines, carbocyanines, merocyanines, styryl dyes and their higher vinylene homologs and wherein said dye is sensitive to light of wave-lengths diiierent from those to which the dyes in said first and second layers are sensitive.

4. The article of claim 1 wherein the support is a transparent plastic material.

5. The article of claim 1 wherein the support is a White opaque material.

6. A method of preparing a photosensitive element comprising a support member and at least two photosensitive layers supported thereon comprising: depositing a binder-free first layer on said substrate from a solution containing a bleach-out dye selected from the group consisting of cyanines, carbocyanines, merocyanines, styryl dyes and their higher vinylene homologs and an organic halogen-containing compound selected from the group consisting of alkyl and aralltyl compounds in which at least three halogen atoms are attached to a single carbon atom, said halogens being selected from the group consisting of Cl, Br and I; removing the solvent from said layer by drying; depositing a photoinsensitive layer comprising a film of clear plastic laid down on said dried layer by applying a solution of said plastic formulated from materials which do not dissolve or penetrate said layer to which the clear plastic layer is applied; and depositing a binder-free second photosensitive layer on said photoinsensitive layer from a solution containing a leach-out dye selected from the group consisting of cyanines, carbocyanines, merocyanines, styryl dyes and their higher vinylene homologs and wherein the solvent for said dye being a non-solvent for the dye in the first photosensitive layer, and an organic halogen-containing compound selected from the group consisting of alkyl and aralkyl compounds in which at least three halogen atoms are attached to a sinlge carbon atom, said halogens being selected from the group consisting of Cl, Br and I and removing the solvent from said second photosensitive layer by drying.

References Cited in the file of this patent UNITED STATES PATENTS Szczepanik May 22, Christensen Nov. 25, Rust et a1. Sept. 15, Seymour Dec. 18, Rogers May 9, Haas et al. July 10, Sprague et a1 Sept. 24, 

1. AN ARTICLE COMPRISING A SUPPORT MEMBER AND AT LEAST TWO PHOTOSENSITIVE LAYERS SUPPORTED THEREON AS FOLLOWS: A BINDER-FREE FIRST PHOTOSENSITIVE LAYER ON SAID SUBSTRATE CONSISTING ESSENTIALLY OF (1) AN ORGANIC HALOGEN CONTAINING COMPOUND SELECTED FROM THE GROUP CONSISTING OF ALKYL AND ARALKYL COMPOUNDS IN WHICH AT LEAST THREE HALOGEN ATOMS ARE ATTACHED TO A SINGLE CARBON ATOM, SAID HALOGENS BEING SELECTED FROM THE GROUP CONSISTING OF CL, BR AND I, AND (2) A BLEACHABLE POLYMETHINE DYE SELECTED FROM THE GROUP CONSISTING OF CYANINES, CARBOCYANINES, MEROCYANINES, STYRYL DYES AND THEIR HIGH VINYLENE HOMOLOGS; A PHOTOINSENSITIVE LAYER OF CLEAR PLASTIC COATED ON SAID FIRST LAYER, SAID PLASTIC HAVING BEEN DEPOSITED ON SAID FIRST LAYER FROM A SOLUTION OF SAID PLASTIC FORMULATED FROM MATERIALS WHICH DO NOT DISSOLVE OR PENETRATE INTO THE FIRST LAYER WHEN THE SOLUTION WAS APPLIED THERETO; AND A SECOND PHOTOSENSITIVE LAYER ON SAID PHOTOINSENSITIVE LAYER, SAID SECOND PHOTOSENSITIVE LAYER CONSISTING ESSENTIALLY OF AN ORGANIC HALOGEN CONTAINING COMPOUND SELECTED FROM THE GROUP, CONSISTING OF ALKYL AND ARALKYL COMPOUNDS IN WHICH AT LEAST THREE HALOGEN ATOMS ARE ATTACHED TO A SINGLE CARBON ATOM, SAID HALOGENS BEING SELECTED FROM THE GROUP CONSISTING OF CL, BR AND I, AND A BLEACHABLE POLYMETHINE DYE SELECTED FROM THE GROUP CONSISTING OF CYANINES, CARBOCYANINES, MEROCYANINES, STYRYL DYES AND THEIR HIGHER VINYLENE HOMOLOGS AND SENSITIVE TO LIGHT OF WAVELENGTHS DIFFERENT FROM THOSE TO WHICH THE DYE IN SAID FIRST LAYER IS SENSITIVE, THE ORGANIC HALOGEN CONTAINING COMPOUNDS IN SAID FIRST AND SECOND LAYERS BEING PRESENT IN AN AMOUND SUFFICIENT TO ACCELERATE THE BLEACHING OUT OF SAID DYES WHEN EXPOSED TO RADIATION ABSORBED BY SAID DYES. 